This invention relates to torque tools and, in particular, to dual or combination torque tools for setting valve clearances on internal combustion engines or other components where feeler gauges are normally used.
Internal combustion engines typically require a specified clearance between the valves and the valve opening mechanisms. Rocker arms are used on many engines to open the valves. One end of each rocker arm engages a camshaft directly, in the case of overhead camshafts, or a push rod in the case of push rod engines. The opposite end of the rocker arm operatively contacts the valve. More specifically, this end of the rocker arm usually has an adjustment screw or bolt. The lower end of the screw or bolt contacts the valve, a cross head for multiple valve engines or other such components associated with the valve. There is usually a lock nut on the top of the screw or bolt above the rocker arm which is tightened to keep the screw or bolt in a desired position. The clearance is set by loosening the lock nut and inserting a feeler gauge between the bottom of the screw or bolt and the valve. The screw or bolt is then tightened or loosened until the mechanic senses the correct amount of drag on the feeler gauge as it is pulled between the screw or bolt and the valve.
After the correct amount of gap is set, the lock nut is tightened. This should be done to a specified torque. However the screw or nut must be held at the rotational position where the gap was set. Accordingly a normal socket-type torque wrench cannot be used since it would interfere with the screwdriver or wrench or the screw or nut. A special crow foot torque wrench is usually used to enable the mechanic to hold the screw or bolt while the lock nut is tightened.
The disadvantage of this technique is not only the requirement for multiple tools. There are also problems in setting the valve clearance within acceptable tolerances. The drag of the feeler gauge may be an acceptable way of measuring the gap for an experienced mechanic when the parts are new. However the task is not as easy for inexperienced personnel, particularly as the parts become worn. They may be pitted or otherwise distorted such that a feeler gauge tends to ride on the rough surfaces instead of measuring the actual gap.
It is therefore an object of the invention to provide an improved apparatus and method for adjusting valves which overcomes deficiencies in the prior art.
It is also an object of the invention to provide an improved apparatus and method for adjusting internal combustion engine valves which does not depend upon the use of feeler gauges or the like.
It is a further object of the invention to provide an improved apparatus and method for adjusting internal combustion engine valves where the bolt or screw on the rocker arm can be rotated with a tool to the required position to set the specified clearance, and the lock nut and can be tightened with the same tool while the bolt or screw is held in the required position.
There is provided, according to one aspect of the invention, a valve adjusting tool for an internal combustion engine having a valve opening member with a male threaded member operatively and adjustably contacting the valve. The tool includes a first member engagable with the threaded member for rotating the threaded member towards or away from the valve. There is means for rotating the first member in a first rotational direction so the male threaded member moves towards the valve and for rotating the first member in a second rotational direction so the male threaded member moves away from the valve. There is means for stopping movement of the first member, as the first member moves towards the valve, when the male threaded member operatively contacts the valve and thereby takes up play between said valve opening member and the valve. There is means for measuring a predetermined amount of rotation of the threaded member, as the threaded member is rotated in the second rotational direction away from the valve, after having operatively contacted the valve, and thereby setting a specified amount of play between said valve opening member and the valve.
There is provided, according to another aspect of the invention, a method of setting a valve clearance on an internal combustion engine having a rocker arm with a male threaded member operatively contacting a valve. The method includes the steps of loosening any lock nut on the threaded member and rotating the male threaded member in a first rotational direction towards the valve until the male threaded member operatively contacts the valve. The male threaded member is then rotated in a second rotational direction, opposite the first direction, for a specified angle of rotation related to the pitch of the male threaded member, such that a specified clearance is set between the male threaded member and the valve.